Moscow’s decision to move unilaterally, without Red Cross involvement, raised questions about its intentions.
Suspicions were running high that the humanitarian operation may instead be aimed at halting Kiev’s momentum on the battlefield.
Ukrainian Prime Minister Arseniy Yatsenyuk declared that the trucks were half-empty and were not going to deliver aid but would instead be used to create a provocation. He said Russia would somehow attack the convoy itself, creating an international incident.
Ukrainian security services chief Valentyn Nalyvaichenko called the convoy a "direct invasion."
NATO’s secretary-general condemned Russia for sending in a "so-called humanitarian convoy." Anders Fogh Rasmussen said Russia committed "a blatant breach" of its international commitments and "a further violation of Ukraine’s sovereignty."
AP journalists following the convoy across rough country roads heard the trucks’ contents rattling and sliding around Friday, confirming that many vehicles were only partially loaded.
Nalyvaichenko said the men operating the trucks were Russian military personnel trained to drive combat vehicles, tanks and artillery.
He insisted, however, that Ukraine would not shell the convoy.
The Red Cross, which had planned to escort the convoy to assuage fears that it was a cover for a Russian invasion, said it had not received enough security guarantees to do so, as shelling had continued overnight. Four troops were killed and 23 wounded in a 24-hour period in eastern Ukraine, the government reported Friday.
The government said it had authorized the entry of only 35 trucks. But the number of Russian vehicles seen passing through was clearly way beyond that.
International monitors said that as of midday, 134 trucks, 12 support vehicles and one ambulance had crossed into Ukraine.
In announcing its decision to act, the Russian Foreign Ministry said: "There is increasingly a sense that the Ukrainian leaders are deliberately dragging out the delivery of the humanitarian load until there is a situation in which there will no longer be anyone left to help."
It added: "We are warning against any attempts to thwart this purely humanitarian mission."
Rebel forces took advantage of Ukraine’s promise not to shell the convoy to drive on the same country road as the trucks. Some 20 green military supply vehicles — flatbed trucks and fuel tankers — were seen traveling in the opposite direction, along with smaller rebel vehicles.
The fighting in eastern Ukraine began in mid-April, a month after Russia annexed Ukraine’s Crimean peninsula. It has killed over 2,000 people and forced 340,000 to flee, according to the United Nations.
Concluding his letter, Major Archbishop Sviatoslav says, “Ukraine needs the effective support of the global Christian community and support of all people of good will. In a media context rife with propaganda we ask you to evaluate information critically. We need your prayer, your discernment, your good words and effective deeds. Silence and inaction will lead to further tragedy. The fate of MA Flight 17 is an example of what may happen if the terrorist activity is allowed to continue.”
Separately, Ukraine’s Ambassador to the Holy See, Tetiana Izhevska, expressed gratitude to Pope Francis for his personal attention and concern about the crisis in Eastern Ukraine and his continued appeals for peace and dialogue to resolve the conflict there.
Izhevska spoke with Vatican Radio Friday about her government’s views on the conflict in Eastern Ukraine and said Kiev believes the situation remains very dangerous with a high risk of a direct Russian invasion.
“Russia,” she said, “is fighting an undeclared war on Ukraine” through its armed support for the pro-Russian rebels…. The probability of a direct Russian invasion is still high.”
At the same time, according to the ambassador, “it’s evident that economic sanctions remain the only efficient tool to influence Russian behavior.”
The Associated Press and Vatican Radio contributed to this report.